Hi,

BIND's default rndc port is 953, but I could not find an assignment for
this in the IANA "Service Name and Transport Protocol Port Number
Registry":

http://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.txt

which shows that well-known ports 914-988 are unassigned.

-- 
Robert Edmonds
edmonds@debian.org